Dec. 14, 1888.] 



SCIENTIFIC NEWS. 



607 



example before us, they are " written specially to meet 

 the requirements of " this examination, " it will be 

 specially helpful for that," and " it will also be found 

 sufficient for the requirements of" the other. 



Several matters call for revision. We object to the 

 ideas of absolute rest and motion in treating of the 

 mechanics of ordinary Euclidian space. Clerk Maxwell 

 tells us that " it is impossible for us to speak of a body 

 being at rest or in motion except with reference, expressed 

 or implied, to some other body." Nor is it scientific to 

 say that "the horizontal direction is the surface that a 

 limited quantity of water assumes when at rest" (the 

 italics are the author's). As an instance of unstable 

 equilibrium, an illustration of a cart is given, in which 

 the centre of gravity is considerably outside the base. 

 The cart is not in equilibrium at all. Some examples 

 are suggestive of "blind mathematics," e.g., a "cylindri- 

 cal tower of the same diameter throughout is 100 feet 

 high, and weighs five tons," etc. Of what material can 

 the author have been thinking ? If of brickwork, it 

 would have a sectional area of about one square foot ; if 

 of cork, it would be only about 75 square feet. One 

 hundred and thirty tons would be near the mark for a 

 brick chimney of this height. 



Plenty of examples might be taken from ordinary 

 engineering practice without imagining so unlikely an 

 instance as ''a rod of cast iron 100 feet long, and cross 

 section 12 square inches, stretches 3 inches under a 

 certain tension." 



The author is not so original and interesting as'Professor 

 Perry, nor so amusing as Professor Oliver Lodge, in their 

 admirable text-books on the same subject, but he provides 

 numerous illustrations and examples, both worked out 

 in full and collected at the end of the chapters. 



Colour : an Elementary Treatise. By Chas. T. Whitmell, 

 B.Sc, F.G.S., M.A. 8vo, 233 pp., 4s. Cardiff: 

 W. Lewis, 22, Duke Street. 1888. 



It would be useless to enlarge on the importance of 

 " colour " as a subject deserving attention, since we have 

 continual evidence of the benefits derived from it, either 

 in the way of enjoyment obtained by seeing the beauti- 

 ful variations of colour in Nature and in the artistic re- 

 productions of them, or in the form of comfort in the 

 agreeable effects produced by the colours introduced for 

 the adornment of our homes, or when it is found in its 

 many useful applications. Although some are satisfied 

 with the mere sensations produced by colour, others, of 

 a wisely more inquiring mind, want to know whence 

 arise these sensations. What is colour ? Why 

 is it produced ? and where does it come from ? 

 To these latter the present volnme will specially 

 recommend itself. This treatise differs from pre- 

 vious treatises on the same subject in following a 

 definite scheme of treatment. The subject-matter is 

 divided roughly into scientific and artistic divisions. In 

 the first of these we find the following points discussed 

 in the order given : nature of colour, production of 

 colour, constants of colour, mixture of colour, results of 

 mixing colours, complementary colours, theory of colour, 

 colour blindness, and systematic classification of colour. 

 The second division includes description of some 

 coloi rs and pigments, colour combinations, small interval 

 and gradation, colour harmonies, and finally painting and 

 decorative art ; whilst in an appendix colour photometry 

 and some other points are treated. Many of the most 

 valuable scientific contributions, such as the work of 



Lord Rayleigh (pp. 36, 60, 86, 90, 107, etc.), of Koenigs 

 (p. 121 et seq.), etc., etc., are set before the reader more 

 fully than in previous books on colour ; whilst Captain 

 Abney's and Major-General Festing's results (p. 235) 

 appear tor the first time in a book of this kind. Many 

 descriptions of experiments are given fully, so as to allow 

 of their being repeated by the reader. This is a great 

 advantage, for, as the author says, " matters which may 

 appear dry and difficult to understand in reading will be 

 found to wear quite a new aspect when tested by ex- 

 periment." In spite of the copious table of contents, we 

 think an alphabetical index would be a useful addition. 



Macaws, Cockatoos, Parakeets, and Parrots. By the late 

 Sir T. D. Lander, Bart, F.R.S.E., and Captain 

 Thomas Brown, F.L.S. With Chapters on Diseases 

 and Cages, from Dr. Karl Russ. Illustrated with 

 Forty Engravings by Joseph B. Kidd, Member of the 

 Scottish Academy of Painting, Sculpture and Archi- 

 tecture. London : Dean and Son. 



This little book opens with an account of the " physical 

 characters of parrots," in which we find no little repeti- 

 tion, sometimes with variations. Thus we read in one 

 paragraph that the birds only lay three or four eggs at a 

 time, whilst on the succeeding page we are told that the 

 number of eggs hatched at a time varies from three to 

 six. The eggs are said, in one place, to be " equally 

 obtuse at both ends." But then follows the information 

 that the eggs are " of the shape of a pear, slightly 

 flattened at the broad end." The anecdote that " Scaliger 

 saw one that performed the dance of the Savoyards, at 

 the same time that it repeated their song," occurs twice, 

 on page 17 and again at page 31. Such blemishes should 

 be eliminated in the very probable case of a second 

 edition. 



It seems to us that the authors form much too low an 

 estimate of the intelligence of parrots. It is easy to say, 

 as do many writers, that their speech is " mere imita- 

 tion." So is that of a young child. We have observed 

 instances of parrots connecting their remarks with appro- 

 priate facts or events, and never uttering them under any 

 other circumstances. Thus our own parrot, on seeing 

 water drawn from a tap, has called out, " Water, water ! 

 Polly wants ! " and has drunk eagerly on some being 

 offered her. This speech has never been taught her, 

 and it is never uttered on any other occasion. If any 

 one comes into the kitchen with a basket or a parcel, she 

 generally says, "What 00 got?" Now, the bird in 

 question is by no means exceptionally clever, and has 

 never undergone any formal instruction. We by no 

 means contend that parrots analyse the sentences 

 they utter, no more than do your children. But we 

 submit that they very frequently understand some par- 

 ticular phrase as a whole, and use it accordingly. We 

 must remember that the parrot has no hereditary apti- 

 tudes to fall back upon. What would be the result if a 

 pair of clever parrots were matched and their young 

 brought up in human society, in a suitable climate, and 

 under kind treatment, is an unsolved but highly interest- 

 ing question. 



The practical portion of this work is much better than 

 the theoretical part. We are glad to see it formally 

 admitted, contrary to the notion of many bird-fanciers, 

 that parrots do drink and require a supply of water. The 

 remarks on the diet and general treatment of parrots are 

 valuable, and will save much misery to the birds, and 

 disappointment to their owners. 



